Water tube boiler



May 15, 1956 H. voRKAUF 2,745,389

WATER TUBE BOILEP.

Filed April 29, 1952 7 1 Fig 1 r .4 @Qi 'g /4 20 United States Patent O 2,745,389 WATER TUBE BOILER Heinrich Verkauf, Berlin-Schmargendorf, Germany Application April 29, 1952, Serial No. 284,875

Claims priority, application Germany May 5, 1951 1 Claim. (Cl. 122-488) The invention relates to a water tube boiler and more in particular to a water tube boiler with a steam separator and with a group of evaporator tubes connected to an upper and lower collector box in which the lower collector box is connected to the Water space of the separator and the upper box communicates with the separator approximately at the height of the mean water level.

The invention aims to provide means for improving the circulation in the evaporator tubes and to relieve the steam separator by pre-separation of boiler water.

The invention contemplates to provide upper collector boxes of two or several groups of tubes and Vto connect the collector boxes so as to discharge into a common,V

non-heated return pipe.

This arranoement oiers the advantage, that a portion of the liquid working Vmedium taken from Athe steambe the lower the more steamfwater mixture enters the return pipe. vWith the loweringgofthe Water level, the quantity of water separated from the steam-water mixture will increase, and,'conseouently, theletect of the return pipe will increase correspondingly. V Such desirable eiect will be obtained by conducting the steam-water mixture fromtwo or more than two groups of tubes into a common return pipe. l l

It is another object of theinvention further t increase the mentioned erect of water separation by so. arranging the collectorboxes that they open in the common return pipe at a predetermined angle, e. g. aV right angle. A discharge into the return pipe in a tangential direction is advantageous as thereby especially much water will be drained.

The invention further aims to improve the pre-separation and direct return of boiler water lay-passing the steam separator, by providing communication of the upper portions of the return pipe with the steam space of the separator through a connecting pipe. This causes steam and water to flow in the upper collector boxes in the same direction. Furthermore, the steam ilowing towards the return pipe takes -the separated water along in the same direction.

Another object of the invention is to design a return pipe or a plurality 'of return pipes together with the downcomers as parts of the boiler frame.

Furthermore objects and details of the invention will be apparent from the description given hereinafter and the accompanying drawing illustrating an embodiment thereof by way of example. ln the drawing:

Fig. l is a diagrammatical illustration of the principle of the invention:

Fig. 2 is a longitudinal section of a boiler according to the invention;

Fig. 3 is a cross-section of the embodiment of Fig. 2 in a horizontal plane;

Fig. 4 is a side elevation of the connection of parts of the boiler of Fig. 2, and

Fig. 5 is a horizontal cross-'section of a modified form` of connection of such parts,v Referring now to the drawing, in Fig. 1, the reference numerals 1 and 2 denote Vtwo groups of water tubes of `4 which only the axes are indicated by dash and dot lines. These tubes may be arranged on the walls of the re space and the groups may be located in planes at a right angle to each other. The parallel water or evaporator tubes 1 and 2 rise from the lower collector boxes 3 and 4, respectively, which may be in the form of pipes, and open into the upper collector, boxes or pipes 5 and 6, respectively. The lower collector boxes 3 and 4 are connected by the downcomer 7 to the water space of the steam separator or header S, whereas the upper collector boxes 5, 6 are connected to the steam separator S approximately at the height of the mean water level. The steamwater mixture created in the evaporator tubes of the groups 1 and 2 flows into the upper collector boxes 5 and 6, which open intoa return pipe 9. The discharge of two jets of a steam-water mixture into the pipe 9 promotes the separation of water byreturning itthroughk that pipe. Inasmuch as the steam can flow only towards the separator 8, the major portion ot the water following the way of least resistance will .iiow towards the re` turn pipe 9 and will, thus, be restored into the circulation` V course on its shortest way, by-passing the separator S.

tion opposite to thatl of the steamr. This isV not harmful `r when the crosssection of .the collector boxes islarge,

that rmeans when the speed of thesteam isfnot'too highs If, however, the speed of the steam -is Vhigh in the uppertion towards thereturn pipe with the result `that the ow collector boxes, the draininggofthe water from thegcol lector vbox :r to the return pipe;9may `be hampered vby the counter ycurrentV of the stearnl yln `such a--caseit` 'is advisable to connect the upperend ofthe-return pipe' bymeans of a connecting pipe 1010 .the steam space of the*` separator 8. Thereby it will be attained )thatV a portion ofthe steaminthe collectorboxlviloivls alsorirrthe direcof the water in that direction will be accelerated. This pre-separation Vrelieves the steam separator 3 quite considerably. The entering steam-water mixture will be of a relatively low humidity, that means it will contain only relatively small quantities of water for the separation of which a relatively small steam space will be sufficient, so that the steam separator can be smaller than generally required for equal evaporation. it will be apparent that the invention renders possible also a reduction of the downcomers 7, since large quantities of circulating water ow back directly through the return pipes 9, and oniy as much boiler water ows to the tube system through the downcomers 7 as corresponds to the quantity of the avorio ing medium entering the separator. in consequence, the number and diameter of the boresin the separator for the connection of the downcomers can be reduced so that the wall of the separator will be less weakened and, therefore, the thickness of the wall may be dimensioned smaller. With small or medium steam output, in general, two downcomers 7 will suffice which may simultaneously serve as supports for the separator S and may be combined with the return pipes 9 and the upper and lower collector boxes or pipes 3, 4, 5 and 6 to form a water cooled boiler frame. In that case, a separate frame can be dispensed with entirely, The frame of pipe members may' support not only the heating surface of the boiler with or without a superheater and feedheater, but also an outer insulation and a sheet metal cover if present.

In the embodiment illustrated in Figs. 2 and 3, there is a front group of tubes 11 and two side groups 12 indicated in Fig. 2 by the dash and dot lines of the tube axes. The

lower tubular collectorV box 13-Vto ythe upper tubular box 14 whereas-the tube groups Y 12` located on the side walls extend from'tlie lower collector boxes 1S to the upperboxes 1'6. According to the Vinventiom-theupper 'col-lector boxes vare connected tothe Y return pipes 9 ,which are located inthe corners 'between the groupsjll rand 12J 'The'nppfer-end of each pipe 97 communicates through a pipe 1Q-with thesteam space of that many modifications and but by the scope of the appended claim. n Y

I claim: v

In a water tube boiler ,the combination of av steam t separator drum includingg-agsteam space and Vawater separator VStvvvliich is supported by the downcomers "7.

The downcomers communicate at their top ends .ivitlrifthcY Vwater space of the separator and through their lower 'por-V tionswith Vthe collector' boxes i5. 'Mostof the steamwater mixture created Vin the tube groups,V 11 and 12 willv Ybe separated Vin the uppercollector boxes. A `portion of the separated wateriflows directlyback through pipe 9 VintogtheV course of circulatiorywhereas the vcreated steam ows from the upper collectorboxes or through the Vpipes 10 to the steam separator. In order to `protect the return pipes k9 against heating, vthe adjacent evaporator tubes 17 Y may be pnovided4 with ribsA 18. Y

The connection of two7or more than two collector boxe Yor pipes with one return pipe in a ycomer point some'- times causes difliculties inthe production so that 'it becomes necessary, to arrange one of lthe pipes 4o set with respectt'o the point .of intersection. kA recommendable Vconnection of 'the upper" ,collector pipesr14, Y16 `with the return` pipe 9`is Vshown in Fig. 4, whereby the mentioned drawback can be avoided. For this purpose, the return torpipe's may VbeiconnectedV tothe return'pipes Y9.v

space, a first group of evaporator tubes in a rst verticalV plane, a second group -of- 'evaporator tubes in a second Y vertical plane Yforming a corner with said Yfirst planer're-v ,Y Vmote from said drum, a lowerV and an upper horizontal collector lboxtforeach of said groupsof tubes having their ends connected .to the associated Vcollector boxes, a verti-rA Y cal non-'heated tube at said corner and 'constituting a re-` turn pipe, said lower collector kboxes being connected with ,n

one of their ends to the lowerY portion of said return pipe, the other end of the lower collector box of said first group being connected to the water space of said drum, said upper collector boxes of bothsaid groups being located in one plane substantially at the height of the meanA watervr level in said drum, and being connected withrone of their ends'to theV upper end portionof saidY return pipeA at right angles Vto the latter, the other end of the upper col-V t lector 4box of said 'rst group being Yconnected 'to said 1 Y drumV substantially at said height of said mean Water level, and `a steam conveying pipe connected to said return pipe with one of its end portions in a vertical ycontinuation of ,y said return pipe above the'connection of saidr upper col- Fig. 5 llustrate'sa moded connection of the, collector A :if pipesliand V156v with the*piece"f19, wherein the collector ,v pipes"dischargejinto` the returnrpipe in: tangential direc-. Y

Y -tionsso1 that the separation vof steam and water moted bya centrifugal Vory slinging effect1^jV e e ,Y Y Y Although I have shown only one embodiment of my. 145

f 5 invention,f it willrbejapparent to Ythose'skilled 'in' the Aart is pro-` lector Vbox'esand with vits oth'err'end tothe steam space Y of said drum, so Vas to cause in each of said uppercollec t'or boxes steam 'to `flow in the 'same' directionk as watertowards said returntpipe.V Y, r f

References Cited in the' of this patent Ur-11rED-sTAfrEs VPARENTS alteration ,thereof are Vpose-v 'l sible without departure-from Vthe essenceY and spirit of .Y Vmy invention which for that reason shalltnot be limited 

